Automatic telephone system



June 10, 1941.

E. JAUCH AUTOMATI C TELEPHONE SYSTEM 3 Sheets-Sheet 1 Filed Nov. '21, 1938 June 10, 1941'.

E. JAUCH AUTOMATIC TELEPHONE SYSTEM Filed Nov. 21, 1932'. 3 Sheets-Sheet 2 INVENTOR:

EUGEN JAUCH %Z M 4 ATTORNEY.

June 10, 1941. JAUCH AUTOMATIC TELEPHONE SYSTEM 1958 3 Sheets-Sheet 3 Filed Nov. 21

INVENTORI, EUGEN JAUCH Patented June 10, 1941 AUTOMATIC TELEPHONE SYSTEM Eugen Jauoh, Berlin-siemensstadnfierinany, as-

signor to Fides Gesellschaft fnrdie Verwaltung und Verwertung von -gewerblichen Schutirechten m. b. 11., Berlin, Germany Application November 21, 1938, Serial No. 241,506 In Germany November 22, 1937 14 Claims. .(Cl. 179,26)

The present invention relates to automatic telephone systems with .main and sub-exchanges in which for the purpose of making a connection between two subscribers .of the same sub-exchange (an internal connection) the selectors are set with the aid of the main exchange.

Arrangementsare .already known in which for making internal connections two selectors are provided in the sub-exchange on a junction line extending between the sub-exchange and the main exchange of which one serves to connect the calling subscriber to the junction line leading to the main exchange, while the other is set .by dialled impulses to select the desired subscriber in the sub-exchange. In these systems aconsiderable number of switching devices are necessary in the sub-exchange, in particular a feeding battery, since only the setting of theselector which selects the desired subscriber is done from the exchange while theselector for connecting the calling subscriber is controlled by local current from the sub-exchange.

Further arrangements have been proposed in which such a great expense on switching devices in the sub-exchange is avoided in that the control of the selector-serving toconnect the calling subscriber is also done from the main exchange. Here, however, two junction lines are used between the main exchange and the sub-exchange in order to make the internal connection,- and the calling subscriberis connected to the first junction line over a selectorincluded in the junction line while the selection of the desired subscriber is carried out by setting the selector in the second junction line.

The present invention describes a method of controlling both selectors from the main exchange over a single junction line.

In order to do this, after the setting of the selector which serves to connect the calling subscriber to the junction line has been controlled over the junction line from the main exchange, in dependence upon the characterizing of a connection with a subscriber of the same sub-exchange switching devices in the main exchange come into effect andinfluenceswitch means in the sub-exchange over the junction line by which a reversal of connectionsis produced in the subexchange so that instead of the selector which is set on the calling subscriber, .the selector serving to select the desired subscriber is brought under the iniiuenceof the main exchange, over the same junction line.

The invention also relates to automatic telephone systems including-main and sub-exchanges in which the separation of traffic ,directions and :the sending of impulses for setting selectors in thesub eexchange isdoneinrthe main exchange.

In systems in which .the trafilc directions are separated in the main exchange, thesendingout of impulses .from the main exchange to the subexchange. controls, either the selector in thesubexchangewhichserves to select-the desired sub- ,exchange subscriber, .or in addition, the selector which carries out theconnection of the calling sub-exchange subscriber by .means of im ulses controlledjby the main exchan e.

In systems of the first kind the sending out of impulses to build up in omin connect sa internal connections; to the ,desired subscriber in -;the sub-exchange .is done either ,by switching me hanism, which, .oni s s ttin acco d n to certa n charac er zati n b n mpu e receive influenced by the calling -su bscriber of the main exchange or similarly by a switching discrimi- ,nator set tor the purpose of separating'thetrafiic directions from the Calling subscribers of the by the impulse selection of the calling subscriber connected to the sub-exchange, sends back the impulses.

In systems of-the second kind the-impulsesnecessary for setting the selector for the purpose of connecting the calling subscriber and for the purpose of selecting the desiredsubscriber, are

produced either by thesetting of different switching mechanism inthe main exchange orthe-same switching ,mechanism serves-t0 produce impulses ,for connecting the callingsubscriber andfor the selection of the desired subscriber; and actually either only .in so-far as it produces the impulses on the setting up of an incoming connection in dependence on the setting of a dialimpulse receiver, while the impulse, sendingforiselecting the desiredsubscriber-for internal connectionsis done .by direct sending back of the selecting impulses after the traific discrimination, orthe switching mechanism also ,sendsthe impulses for building up the internal connection. In the lattercase it must be setfor allimpulsesending;andactually only for the connection of the calling subscriber in the first place and then for the selectionoof the desired subscriber according to a ,certain characterization from. a switching discriminator infiuencedrto separatethe' traiiic directions of the calling subscribers.

The present invention describes another method which consists in connecting the operating magnets by switching devices influenced in the main exchange in dependence on the setting of a switching mechanism in an operating circuit controlled by the dial impulses for the separation of the traffic directions or in an automatic operating circuit-to produce impulses for setting the selector in the sub-exchange.

In the arrangement according to the invention, by using for example, the switching mechanism for separating traflic directions and producing impulses for selecting the desired sub-exchange subscriber in the making of an internal connection, the advantage is produced in that the expense on special switching mechanism is avoided if the switching technique does not allow the known repeated use of theiswitching mechanism serving to connect the calling subscriber. This is the case, for example, when this switching mechanism by means of its setting, characterizes the calling subscriber in the mainexchange for some purpose or other, e. g, metering his conversation. In this arrangement three switching mechanisms are necessary, namely, for connecting the calling subscriber, for separating the trafiic directions, and for selecting the desired subscriber. By using the arrangement according to the invention, however, the last two functions can, for example, be carried out by 'a single" switching mechanism so that altogether only two switching mechanisms are necessary.

In systems in which the calling subscriber is connected, not by means of an impulse sent out by a switching mechanism, but by the selection of the desired subscriber by such a switching mechanism then, in general, only a single switching mechanism is necessary; and this is also true in the reverse case.

The invention also relates to automatic telephone systems having main and sub-exchanges in which connections between two subscribers of the same sub-exchange are made with the aid of the main exchange over a junction line extending between the main and sub-exchange.

In these systems special difficulties arise in effecting the further switching operations necessary for building up the connection over the connecting line between the main and sub-exchange after the selection of the desired exchange subscriber. These switching operations in particular concern the sending out of the calling current disconnection of the calling current, and maintaining of the connection until the desired subscriber replies. If, for example, the calling subscriber is connected after the selection of the desired subscriber to the same junction line between the main and sub-exchange to which also the desired subscriber is to be connected, then on using the usual call connections the calling current is disconnected as soon as it is sent out over the speaking loop of the calling subscriber. This speaking loop must therefore be interrupted after the selection of the desired subscriber in order to prevent this premature disconnection of calling current. The arrangement is not, however, favorable for this interruption since the existence of the speaking loop is necessary in order to maintain the connecting path which has been set up.

In some systems, therefore, the calling sub-exchange subscriber is only disconnected during the sending out of calling current to the sub-exchange from the junction line, and during this time the relay in the main exchange serving to maintain the connection is transitorily connected in the holding circuit so that during each pause in the calling current the calling subscriber is again connected to the junction line so as again to bring the relay serving to maintain the connection, under its influence. Since such arrangemerits, disregarding the extra expense on switching devices, are inconvenient on account of the calling subscriber having no influence in the course of the switching operations during the period in which he is completely disconnected, other arrangements have been proposed in which after the selection of the desired subscriber the junction line between the main exchange and the sub-exchange is interrupted so that the circuit for maintaining the connection extends over one conductor under the influence of the calling subscriber and the calling current extends to the desired subscriber over the other conductor.

Further, arrangements have been developed which avoid a premature disconnecting cf the calling current by the calling subscriber by having them not brought about by a simple loop formation but by a transitory production of impulses which is initiated on the lifting up of the receiver so that the calling subscriber ah'eady connected to the junction line cannot disconnect the calling current, but this can only be done by the desired subscriber who, on his reply, by lifting up his receiver produces the necessary impulse. This arrangement requires a special construction on the subscribers set in order to bring about a transitory production of an impulse when the receiver is removed.

The present invention indicates another method which according to Which switching arrangements come into effect after the characterizing of the desired sub-exchange subscriber,-

which by influencing the switching devices in the sub-exchange so change the resistance ratio in the loop of the calling subscriber that over this, switch means in the main exchange serving to maintain the connection are operated, while switching means in the same circuit for disconnecting the calling current only come into effect on the reply of the desired subscriber.

The invention also relates to automatic telephone systems with main and sub-exchanges in which connections between subscribers of the same sub-exchange are metered by meters arranged inthe main exchange.

If in the making of such a connection the calling subscriber accidentally dials his own call number instead of the call number of the desired subscriber the operation of his meter arranged in the main exchange is prevented.

Arrangements are already known for this purpose, for several subscribers connected to a comthere is no metering action in the mainexchange.

The present invention without undertaking any special construction of the subscribefls loop subscribers set.

- prevents a metering action when the subscriber dials his own call number in that by the setting of the switch mechanism for charaoterizingthe desired subscriber in agreement with the switching devices for characterizing the calling subscriber switch means in the main exchange are influenced which prevent an operation of the meter associated with the calling subscriber in the main exchange.

Referring to the drawings, Fig. 1 is a circuit diagram of the apparatus at the sub-exchange, and Figs. 2 and 3 combined disclose a circuit diagram of the apparatus at the main exchange.

As an embodiment the sub-exchange UA is shown in the drawings which is connected over a junction line ac /b1; with a main exchange HA. Two selectors AS and LW in the sub-exchange are associated with this junction line by which the selector AS (wipers-asl/asii) is set on a calling subscriber while the other selector LW (wipers lwl/lwd) serves to select the desired subscriber. The control of the two selectors is done from the main exchange HA. This takes place in such a manner that on the ,call of a subscriber in the sub-exchange UA the call relay X in the main exchange is first energized over the junction line by which a switch mechanism KW (wipers kwl/kwS) is set in operation and while it is stepping on, produces impulses which are sent out to the sub-exchange UA in order to set the selector AS in this exchange on the calling subscriber. When this has been done, by means-of a test relay P in the main exchange energized over the junction line the mechanism KW in the main exchange is brought to a standstill and the impulse sending interrupted: the

selector AS in the sub-exchange UA, thus remains on the contacts of the calling subscriber. On a setting of the switching mechanism KW in the main exchange EA to correspond with the calling subscriber the meter in the main exchange corresponding to the calling subscriber is'connected at the same time. The calling subscriber can now, by sending out impulses, set up the desired connection and in fact can make connections over the main exchange HA as well as connections to subscribers in the subexchange. In order to separate these two traffic directions in the-main exchange a further switch mechanism MW (wipers 'mwl/mwfi) is provided which is stepped on by the individual impulse series sent out from the calling subscriber. When by means of these impulse series a connection to a subscriber of the same sub-exchange is characterized the selector of the main exchange which is set in preparation by these impulse series, is released and after the characterizing of the desired subscriber, impulses are sent out from the switch mechanism MW, serving to separate the trafiic directions, to the subexchange UA, in order to set the selector LW serving to select the desired subscriber of this After the impulses have been sent out the sending out of .the calling current to the desired subscriber and on his reply the completing of the speaking connection between the calling and the called subscriber takes place. It will be seen that all the switching operations for the setting up of this connection are controlled from the main exchange HA so that the feeding current for operating the switching devices during the setting up of a connection is completed in the main exchange. In the subexchange UAthere isno feedingcurrent battery.

Setting up on internal connection Since the scope of the invention is more especially concerned with the setting up or a .connection between two subscribers of the same sub-exchange, this will now be described in detail.

When the system is not in use the relays TI to T3 in the sub-exchange UA are energized over the lead an of the junction line; and this circuit actually extends over: earth, battery, relay X, contact H8512, wiper kw3 of the switch mechanism KW in setting 0, contacts 251*2, '22s, 23M, Zim, lead at of the junction line, contacts H1762, liiui, wiper Zw'l of the selector LW in setting 0, wiper as! of the selector AS insetting 0, relays Tl .to T3, earth. In this circuit only the relays T! to T3 are energized so that, as shown, the contacts of these relays are closed in the normal condition of the system. .All the subscribers of the sub-exchange UA are accordingly multiplied to the conductor at of the junction line.

When new for example the subscriber Tn! lifts up his receiver the following circuit is made: earth, battery, relay X, contact H632, wiper low-3 of the switch mechanism KW in setting 0, contacts 252'2, 22s, 23u2, 21m, conductor. an of the junction line, contacts 13112, Jul, wiper Zwl, of the selector LW in setting 0, wiper asl of the selector AS in setting 0, wiper lw 3 of selector LW in setting 0, wiper-as3 of the selector AS in setting 0, resistance Wil, subscriber Tn'l, contact lBtl, wiper cs2 of the selector AS in setting 0, contacts mi, 6112, Bill, relay RI, earth. In this circuit the relay X operates and connects itself in the holding circuit over its contact Il'lx, the resistance Wil i and the Wiper kw! of the switch mechanism KW in setting 0. By opening the contact ll6zr, the normally existing circuit for the relays Tl to T3 mentioned previously is interrupted so that now over the contact 4H the rotary magnet Da's of the selector AS in the subexchange is connected to the lead b1) of the junction line. Over the lead in) the following circuit is made: earth, battery, winding I of the relay K, wiper 16102 of the switch mechanism KW in setting 0, contacts 12g, 383/, lead be of the junction line, contacts 5ul, 4H, contact 3dlw of the rotary magnet Dlw, wiper 21.04, of the selector LW in setting 0, contact l'rll, rotary magnet Dds of the selector AS, earth. In this circuit only the relay K operates so that the following circuit is set up: earth, battery, rotary magnet Dkw, contacts I241), l'llk, H2q, l33a, earth. In this circuit the rotary magnet Dlcw is influenced so that the switch mechanism KW executes a single step. The rotary magnet Dlcw on its energizing closes thecontact 3lldlcwso that over this contact and the resistance WM, the winding I of the relay Y is energized. By the closingof the contact 39y the following circuit is set up: earth, battery, resistance Wi l, contacts 34q, 39:], lead be of the junction line, contacts 5ul, 4t], contact 341110 of the rotary magnet Dlw, wiper 1204 of the selector LW in setting 0, contact -lrll, rotary magnet Das of the selector AS operates and steps on the selector AS by a single step. In the'main exchange HA by the opening of the contact 151 on the energizing of the relay Y the relay K is deenergized so that by the opening of contact I I lie, the rotary magnet Dkw of the switch mechanism KW in the main exchange is disconnected. As a result, contact 3lldkw is alsoopenedsoithat irelay Y is deenergized and by the opening .of athe contact 39y the rotary magnet Das of the selector AS in the sub-exchange is disconnected. If the calling subscriber TnI has not yet been reached by the selector AS the interaction between the relays K and Y and the rotary magnet Dlcw begins again in order to step on the switch mechanism KW in the main exchange and the selector AS in the sub-exchange. Since, however, the calling subscriber 'I'nI has already been reached after a single step of the selector AS in the subexchange UA, after this stepping motion, the following circuit is made: earth, battery, resistance Wi l, contact ZSdicw of the rotary magnet Dkw, winding I of the relay A, windings II and I of the relay P, wiper lcw3 of the switch mechanism KW in settings I to II, contacts 251'2, 22s, 23142, 2Im and 20k, lead av of the junction line, contacts I3r2, IDuI, wiper mi of the selector LW in setting 0, wiper asI of the selector AS in setting 1, subscribers loop TwI, wiper cs2 of the selector AS in setting 1, contacts MI, 6142, BM, relay RI, earth. I

In this circuit the relay P at once operates, and after the short-circuiting of the high resistance Winding I over the contact 32p in the above mentioned circuit, the relay A is energized. On the opening of the contact I241: further operation of the rotary magnet Dlcw is prevented. Relay K is maintained energized over: earth, battery, winding I of relay K, wiper IcwZ of switch mechanism KW in settings 1 to 11, contact 15y, wiper kwI of the switch mechanism KW in settings 1 to 10, earth.

In the sub-exchange UA the relay RI is transitorily energized in the above mentioned energizing circuit of the relay P in two stages: it operates the contacts marked rI2. In this way the short circuit for the windings I and II of the relay UI at the contacts I31'I2 and 6H2 is transitorily removed so that the relay UI is also energized in the circuit of the relay PI described, By closing the contact Sui the conductor ho is switched through to the calling subscriber, while by the opening of the contact 8ul the relay BI is disconnected. The short-circuiting of the windings I and II of the relay UI does not take place, however, since the contacts IuI and IUuI- are open.

In the main exchange HA, in the meantime, after the energizing of the relay P by the closing of the contact 56p, a bridge is connected for the speech conductor over the windings II and III of the relay K since the preselector VW is set into operation in known manner and hunts for a free connecting line, for example to a first group se-.-

lector in the main exchange, If such a line is found, then in known manner relay T is ener ized and stops the preselector VW. Over the wiper kw4 of the switch mechanism KW which together with, the selector AS in the sub-exchange UA rests on the contact I, the meter El 01 the calling subscriber in the main exchange HA is connected. Further, in the main exchange after the energizing of the relay A the following circuit is completed: earth, battery, winding III of the relay P, co tact 86p, winding I of the relay F; contacts 19a, 1811, 12k, earth. In this circuit the relay F is energized. Moreover, over the contact I02a the following circuit is completed: earth, battery, Winding I of the relay 0, contact 88M I, wiper mw3 of the switch mechanism MW in setting contacts 957, 99m, 911), winding II of the relay C, contact 32a, earth. In this circuit the relay C is energized.

If the calling subscriber TnI- wishes to speak t the" subscriber TnIII in this own sub-exchange "UA he must select the number 403 222/0. The

first six trains of impulses influence the individual dial impulse receivers in the main exchange one after another and at the same time the switch mechanism MW, while by means of the last digit 0 only the switch mechanism MW in the main exchange is operated.

The switching operations which are carried out by the individual digits of the above mentioned number are as follows:

By means of the first impulse series consisting of four impulses the circuit of the relay A energized over the subscribers loop is interrupted four times so that by the corresponding interruption of the bridge across the windings II and III of the relay Kat the contact 54a the first dial impulse receiver in the main exchange is influenced in known manner. Moreover, by the opening and closing of the contact I 33a the rotary magnet Dmw of the switch mechanism MW is energized four times over: earth, battery, rotary magnet Dmw of the switch mechanism MW, contacts I268, I270, Iiik, II2q I33a, earth. The switch mechanism MW reaches its fourth contact setting so that accordingly its wiper mw3 for example comes to rest on the contact nI, During the impulse series the relay V is energized as a slow relay by the connection of its winding I over the contact I'iclmw of the rotary magnet Dmw, so that over contact 9812 and the contact I50 a holding circuit for the windings I and II of the relay C is closed during the impulse series. At the end of the impulse series the relay V restores with a delayed release so that now the following circuit is completed: earth, battery, winding I of the relay HI, resistance WzI i, contact B'IhIZ, wiper mw3, of the switch mechanism MW on the contact nI, contacts 961', 99m, 971), winding II of the relay C, contact H3211, earth. In this circuit the relay C is maintained energized. Also the relay Hi on the first step operates its contact indicated by hi I. A holding circuit is closed for the relay HI over: earth, battery, winding I of the relay HI, resistance Wild, winding II of the relay I-II, contacts I340, 94h, earth.

The second impulse series consisting of ten impulses brings about a setting of the second dial impulse receiver in the main exchange in corresponding manner bythe energizing and dealergizing of the relay A and a further setting of the switch mechanism MW, so that this moves from its zero setting of its wiper 111103 on to the contact 11.2. The relay V is energized during the impulse series in the same way so that during this period the above mentioned holding circuit for relay C is closed. When at the end of the impulse series the relay V is disconnected the following circuit is completed: earth, battery, winding I of the relay HI, contacts 8IhI I, 83h2I, Wiper mw3 of the switch mechanism MW on the contact 122, contacts 957', 99m, 9711, winding II of relay C, contact IIlZa, earth. In this circuit the relay C remains energized while relay HI energizes for the second time and operates its contact indicated by M2. The energizing in the sec- 0nd stage is maintained in the circuit already described over contacts 9th and I340.

The next impulse series consisting of three impulses infiuences the third dial impulse receiver in the same manner in the main exchange as well as the switching mechanism MW till the latter reaches the contact 11.3. The energizing of the relay C is maintained by means of the relay V energized during the impulse series in the manner already described. At the end of the impulse series, the relay V is again disconnected so that the following circuit is completed: earth, battery, winding I of relay H2, resistance Wi-I-5, contacts 8471.22, '86hI2, wiper mw3 of the switch mechanism MW on the contact n3, contacts 967', 99m, 9112, winding II of the relay C, contact I92a, earth. The relay C remains energized in this circuit when the relay H2 is energized in the first stage so that it operates its contact indicated by 71.2 I. A holding circuit for the relay H2 extends over earth, battery, winding I of the relay H2, resistance W215, winding II of the relay H2, con tacts 93iz2I, 84114 I, earth.

The fourth impulse series sent out by the subscriber which consists of two impulses causes a fourth dial impulse receiver in the main exchange to be influenced and the switch mechanism MW to be displaced by two steps so that the wiper mw3 reaches the contact M. The relay C also remains energized since the relay V is again energized during the impulse series so that after the completion of the impulse series in View of the denergizing of the relay V the following circuit is completed: earth, battery, winding I of the relay H2, contacts 82h2l, 85b3, wiper mw3 of the switch mechanism MW on the contact n4, contacts 867, 99m, 9112, winding II of relay C, contact IBZa, earth. The relay C remains energized in this circuit while the relay H2 is now operated in the second stage. operates its contact indicated by 71.22. A holding circuit for maintaining the relay H2 energized in the second stage, extends over: earth, battery, winding I of relay H2, resistance Wile,

winding II of relay H2, contacts Qi'ihZI, Q 'ihll,

earth.

The fifth impulse series consisting of two impulses influences the fiith dial impulse receiver and moreover steps on the switch mechanism MW by two steps to the contact n5. Over this wiper after the deenergizing of the relay V and the completion of the impulse series the following circuit is made: earth, battery, relay H3, contact 9871.22, wiper mw-3 of the switch mechanism MW on the contact n5, contacts 969', 99m, 9112, winding II of the relay C, contact I02a, earth. The relay C remains energized in this circuit; moreover, there follows an energizing of the relay H3 which is maintained in the following circuit: earth, battery, relay H3, contacts BiihZZ, I32h3, resistance W213, contact I3Ilf and Wiper 'mwfi of the switch mechanism MW in settings I-II, contact 1270, earth.

By the last impulse series consisting of two impulses the sixth dial impulse receiver is set in the main exchange for the purpose of discriminating between the trafiic directions, and the switch mechanism MW is displaced by two steps so that its wiper mw3 reaches the contact 2'. After the deenergizing 0f the relay V energized during the impulse series, the following circuit is completed: earth, battery, winding I of relay J. contact 89713, wiper 111.103 of the switch mechanism MW on the contact 1', contacts 969', 99m, 911), winding II of relay C, contact 32a, earth. On the energizing of relay J the above described circuit extending over the wiper mw3 of the switch mechanism MW is interrupted and on the closing of the contact H257 a circuit is formed over the wiper mw i of the switch mechanism MW which extends over: earth, battery, winding I of relay J, wiper of the switch mechanism MW in setting contacts I657, fiSm, Bio, winding II of relay C, contact ma, earth. In this circuit relays J and C are maintained energized.

Accordingly, it

On the opening of contact 517' the bridge across the windings II and III of relay K is broken so that the selector which has been set in the main exchange is released. v

By means of the impulses sent out up to this point the fact that the calling subscriber TnI wishes to make a connection to a subscriber in his own sub-exchange UA has been indicated. He must now send a further impulse series, in order to select the desired subscriber which in the present case since it is the subscriber TnIO who is desired, consists of ten impulses. This impulse series only influences the switch mechanism MW in the main exchange; and actually this is stepped on from the previously reached setting (contact 1') so that the wiper mw I of the switch mechanism MW reaches the contact 9 owing to this impulse series. During the impulse series the relay V is energized for the purpose of maintaining the relay C energized, as has been described several times already, so that after the completion of the impulse series, in view of the deenergizing of the relay V the following circuit is completed: earth, battery, winding III of relay S, relay U2, wiper mw l of switch mechanism MW on the contact 9, contacts I057, 99m, 9711, winding II of relay C, contact Ill2a, earth. In this circuit the relay C'is maintained energized and therelay U2 is operated. The energizing of relay S does not take place in this circuit. After the energization of the relay U2 the winding II of the relay C is short circuited so that it restores. The relay J on the other hand remains energized in the following circuit: earth, battery, windings I and III of relay J, contacts IMJ', IElZa, earth. The relay U2 is maintained energized over: earth, battery, winding III of relay S, relay U2, wiper miw l of the switch mechanism MW on the contact 9, contacts IiiBuZ, IBM, IBM, earth.

Meanwhile, in view of the energizing of the relay'U2 the short circuit of resistance Wi3 at contact 23u2 is removed and moreover by the opening of contact 4Iu2 the earth connected to the lead In: over the winding III of relay A has been disconnected so that in the sub-exchange UA the relay UI is deenergized. In this way, the following circuit is completed: earth, battery, resistance Wi4, contact 29dkw of the rotary magnet Dlcw, winding I of relay A, contacts 3 If, 32p, wiper kw3 of the switch mechanism KW in settings l11, contacts 2512, 22s, resistance Wi3, contact 2070 or 2 Im, lead av, contacts I3rl2, Iflul, wiper lwI of selector LW in settingO, wiper ml of selector AS in setting 1,.subscriber TnI, wiper cs2 cf selector AS in setting 1. contacts 'Iul, 6M2, 8ul, relay RI, earth. In this circuit relay A is maintained energized While the relay RI is energized in the first stage and operates its contacts indicated by H I On the closing of the contact IilrII the rotary magnet Das of the selector AS in the sub-exchange UA is shortcircuited and by the'opening of the contact I H I the short circuit for the rotary magnet Dlw of the selector LW is removed so that now in the sub-exchange UA the rotary magnet Dlw is ready for operating and the conductor bv in the junction line is connected to the main exchange.

Meanwhile, in the mainexchange I-IA by the opening of the contact I34cafter the short-(sircuiting of the winding II of relay C the relay HI is disconnected, and by the opening of contact 94hII brings about the deenergizing of relay I-I2. By the opening of contact 99h22 the relay H3 is disconnected. After the closing of contacts 9Ic and 92h2I the relay HI is again energized over: earth, battery, winding I of relay HI, resistance Wild, winding II of relay I-II, contacts 9Ic, 92h2I, wiper mwZ of switch inechanism MW in setting 111, contact IfiIld-mw of the rotary magnet Dmw, earth. By the closing of the contact I08h3 after the deenergi'zing of relay H3 the following circuit is completed: earth, battery, rotary magnet Dmw of the switch selector MW, contacts I268, I 257, I I lie, I I2q, IIIIuZ, I 88713, earth. Inthis circuit the rotary magnet Dmw is'energized so that the switch mechanism MW executes a further step. On the energizing of the rotary magnet Dmw an energizing of the relay Y also takes place over: earth, battery, resistance Wi l, contact 2Bu2, contacts Z'Idmw of the rotary magnet Dmw, winding I of the relay Y, earth. By the closing of the contact 39y the following circuit is completed: earth, battery, resistance Wi l, contacts 34g, 393 lead In; of the junction line, contacts 5uI, ItI, rotary magnet Dlw of the selector LW in the sub-exchange UA, contact I9rI I, earth. The rotary magnet DZw operates in this circuit and steps on the selector by one step. At the same time as the stepping motion of the switch mechanism MW in the main exchange the selector LW in the sub-exchange UA is accordingly moved one step. This stepping of theselector LW and the switch mechanism MW, which in the manner already described is brought about by the alternate play between the relays K and Y in connection with the rotary magnet Dmw of the switch mechanism MW, continues until the desired subscriber has been reached... In the present case the stepping action ceases after a single step. After one stepping movement the wiper 192105 of the switch mechanism MW reaches the contact s so that over this wiper the following circuit is completed: earth, battery, windings III and, II of relay S, wiper mw5 of the switch mechanism MWcn the contact s, contacts I03u2, Illlj, I021, earth. In this circuit the relay S is energized so that by the opening of contact I268, the rotary magnet Dmw of the switch mechanism MW is disconnected and further stepping of the switch mechanism MW and thus also the selector LW in the sub-exchange UA is suppressed.

In the sub-exchange UA after the stepping of the selector LW the short circuit for the resistance W12 is. removed at thewiper IwI so that the relay RI .can be maintained energized over the subscribers loop of the calling subscriber TnI and this resistance Wi2 only in the first stage, even when the resistance Wi3 is shortcircuited. The maintaining of the connection set up, depends upon the calling subscriber in the following circuit: earth, battery, resistance Wit, contact 29dlcw, winding I of the relay A, contacts 3|), 32p, wiper kw3 of the switch mechanism KW in settings 1 -1 1, contact 25r2, winding II of relay J, resistance Wi3, contact 2010 or 2 Im, lead av of the junction line, contacts I3rI2, IIluI, resistance Wi2, contact I2dlw of the rotary magnet Dlw, wiper asl of the selector AS in setting 1, subscriber Tnl, wiperasZ of the selector AS, in setting 1,c,ontaots1ul,,6rl2, 8uI, relay RI, earth. In this circuit therelays A and J are maintained energized by the calling subscriber and hence, the connection is maintained.

Meanwhile, in the sub-exchange after the energizing of the relay S, before the slow relay U2 restores after the stepping on of the switch mechanism M,W,,the following circuit is completed: earth, battery, windings I and II of the e y R2, contacts II8s, H90, I22u2, earth. The relay R2, by closing its contact 2412, connects calling current to the lead av of the junction line which reaches the desired subscriber over the following circuit: earth, battery, ringing current, resistance Wz'8, contact 247"2, Winding II of relay J, resistance Wi3, contact 2070 or 2Im, lead at of the junction line, contacts I 3H2, Iilul, wiper lwI of the selector LW in setting 1, subscriber TnIO, wiper 12122 of the selector LW in setting 1, con tacts 'IuI, 5H2, 8uI, relayRI, earth. After the release of the relay U2 the further extension of the call results by the energizing of the relay R2 over: earth, battery, windings I and II of relay R2, contacts I I 83, N90, I 2Iu2, slow interrupter LU, earth. During the sending out of calling current by each operation of relay R2 the energizing current extending over the junction line and contact 2512 passes over the contact 24r2 and resistance Wit, so that during the sending out of the calling current the maintaining of the connection by energizing the winding II of the relay J is made possible over the loop of the calling subscriber. The calling subscriber therefore has the possibility during the sending out of calling current, of controlling the supervising the circuit for maintaining the connection without disturbing the sending out of calling current to the desired subscriber by means of his speaking loop. If he wishes to hang up the receiver, then in view of the interruption the loop connection is released. If the desired subscriber replies during a pause in the calling current, by lifting up his receiver the disconnection of calling current takes place by the completion of the following circuit: earth, battery, resistance WM, contact 29dlcw of the rotary magnet Dkw, winding I of the relay A, contacts 3Ij, 32p, wiper 70103 of switch mechanism KW in settings 1 to 11, contact 2512, winding II of relay J, contacts 23u2, 20k or 2Im, lead av of the junction line, contact I3rI2, IIIuI, wiper ZwI of the selector LW in setting 1, subscribers loop TnIIJ, wiper Zw2 of the selector LW in setting 1, contacts MI, 5112, SM, relay RI, earth. If the reply takes place during the sending out of calling current the necessary battery potential is not connected over the contact 25r2 but over the contact 2M2 and resistance WiB. In this circuit the relay RI operates in the second stage so that at the contacts 6112 and I3rI2 the short circuit for the windings I and II of the relay UI is removed. The relay UI operates the circuit mentioned and connects the conductor Zw by closing the.con tact SuI. The relay RI is disconnected by the opening of contact 8uI; the resistance W12 is short-circuited over the contact II uI. The holding circuit for the relay UI now extends over: earth, battery, resistance W14, contact 29dlcw of the rotary magnet Dlcw, winding I of relay A, contacts SI), 3210, wiper 701.03 of the switch mechanism KW in settings 111, contact 25r2, winding II of the relay J, contacts 23u2, 26k or 2Im, lead a2; of the junction line, winding I of the relay UI, contact IIuI, contact I 202220 of the rotary magnet DZw, wiper asl of the selector AS in setting 1, calling subscriber Tnl, wiper cs2 of the selector AS in setting 1, or wiper ZwI of the selector LW in setting 1, desired subscriber Tnlll, wiper 1102 of the selector LW in setting 1, Winding II of relay UI, contact 9uI, lead be of the junction line, contacts 38y, 4Iu2, 43p, 45s, winding I of the relay M, earth. In this circuit the relay M operates. By the closing of contact 68m the winding I of relay S is short-circuited, so

that in view of thezincrease in current the meter 2! of the calling: subscriber isinfluenced overz.

earth, battery, winding II of relay T, meter ZI,.

wiper k i of switch mechanism KW in setting 1, contacts 69s, 68m, 667', earth. Since on the operation of the relay M at contact 99m theholding circuit of the relay S is disconnected (earth,

battery, windings III and II of relay S, wiper 1721.05 of switch mechanism MW on the contact 5, contacts I 057', 99m, 910, winding II of relay C, contact IIJZa earth) the relay S restores. In view of the contact Has a further influencing of the relay R2 and hence a further sending out of calling current, is prevented. The relay M is maintained after the deenergizing of relay S over: earth, battery, winding II of relay M, contact I3Im, resistance W213, wiper mwfi of the switch mechanism MW in settings 111, contact 7270, earthr The winding III of the relay A is connected to the conductor 171) after the deenermaintains the connection which is short circuited over contact 44s. The relay J is, however, maintained energized over the windings I and II in the following circuit: earth, battery, windings I and III of the relay J, contact iiil y', I'fiZa, earth.

The control circuit for maintaining theconnection which serves at the same time to feed both subscribers TTLI and TnIB is as follows: earth, battery, resistance Wit, contact 29dkw of the rotary magnet Dlc'w, winding I of the relay A, contacts My, 32p, wiper 701.03, of the switch mechanism KW in settings 1-11, contacts 2512, 22s, 23202, 2%, lead at of the junction line, winding I of the relay UI, contact IIuI, contact IZdZw of the rotary magnet DZw, wiper asl of the selector AS in setting I or wiper 1112! of the selector LW in setting 1, subscriber TnIO, wiper 2202 of the selector LW in setting 1, winding II of relay UI, contact Qul, lead be of the junction line, contacts 38y, tIuZ, 43p, ids, winding III of relay A, earth. In this circuit themaintaining of relay A energized, in order to maintain the connection, is the standard method.

It should be noticed that after the deenergizing of the relay S after the reply of the desired subscriber Tnli'i the switch mechanism MW is connected in its normal position and the following circuit is completed: earth, battery, rotary magnet Dmw, contacts I258, I290, I28hl I, I09u2, M33713, earth. The energizing and deenergizing of the rotary magnet Dmw in this circuit is produced by the contact IZBhII which on the energizing of the rotary magnet Dmw opens the contact Ithidmw and thus disconnects the relay I-II whereby by the opening of the contact I 26ml the rotary magnet Dmw is deenergized so that over contact I fiiidmw relay HI is again connected. This alternate operation and release continues until the wiper mwZ of the switch mechanism MW has left the contact segment I--II so that further operation of relay III is prevented.

When at the end of the conversation both subscribers hang up their receivers the above described circuit for maintaining the connection is interrupted. In this way the relays A and UI are immediately disconnected; relay J restores on the opening of contact IIIEa. Finally, in a manner which is of no interest here, the relays F, P and M are disconnected so that the following circuit is completed: earth, battery, rotary magnet Dkw of the switch mechanism KW, contacts IZ Ip, IIIic, IEEq, I33a, earth. By the continued energizing and deenergizing ofv the rotary magnet Dkw described in the case of the stepping movegizing of the relay S instead of the relay M which ping on of the switch mech'anism.KW" takes'place at the same. time, as described: above, overfth'e contact say. and .the conductor. be of the junction line, impulses are sent out to: the sub-exchange. By means of these impulses the rotary magnet Dlw of the selector LW is influenced" so that the selector LW is stepped on in the sub-exchange. When this selector has reached its rest position the wiper 1104 of the selector LW stands in its zero position so that rotary magnet Dlw is shortcircuited and further influencing by impulses from the main exchange is prevented. The relay X is disconnected when the wiper lcwl reaches the segments I-Iil. Since the selector AS in the sub-exchange UA still has not reached its rest position the switch mechanism KW in the main exchange I-IA steps on past zero position by action of the relay K and sends further impulses to the sub-exchange UA, by which now over the conductor b1) of the junction line the rotary magnet Das of the selector ASis operated. When this selector has also reached its rest position the normal circuit described at the beginning is completed and extends over: earth, battery, relay X, contact c, wiper kw3, of the switch mechanism KW in setting 0, contacts 25r2, 22s, 23'u2, 26k or 21m, lead av of the junctionline, contacts I 3112, Iiiul, wiper lwI' of the selector LW in setting 0, wiper asI' of the selector'AS in setting 0, relays TI, T2, T3, earth. In this circuit only the relays TI to T3 operate, and by opening the contact 4H disconnect the rotary magnet Bar of the selector AS from the conductor he. Relay K can now no longer be energized over conductor bu sov that the switch mechanism KW should it be in its normal position, is not stepped on any further. On the other hand, if the switch mechanism has notyet reachedits normal position relay K is' energized and deenergized' over the wiper 70102 in setting 1-11 in combination with relay Y and the rotary: magnet Dkw tilIthe switch mechanism KW has reached its normal position.

vretention of metering of the subscribers number Let us assume that the callingsubscriberin making a connection to the desired subscriberswitch mechanism MW previous to the selection of the subscribers own digit rests for example, with its wiper mw5 on the contact 1'. When the calling subscriber now selects the digit'l, i. e. his own connection, the switch mechanism MW makes one step forward. Among other operations which take place the wiper mw 5 reaches the setting 0 so that after the deenergizing of the relay V at the termination of the impulse series, the following circuit is made: earth, battery, winding III of relay S, contact I942), wiper 76105 of the switch mechanism KW in setting 1, wiper mw5 of the switch mechanism MW in setting 0, contacts I057, 99m, 9112, winding II of relay C, contact I02a, earth. In this circuit the relay S operates while the relay C in contrastv to the switching operations when the correctnumber is selected, remains energized. As a result the rement together. with. the relays K and Y, a steplays I-Il, H2 and H3 do not restore as the contact I340 is maintained operated. The engaged signal is transferred to the Winding II of relay A over the contacts H8s and I200, and by means of the inductive effect of the relay A on the winding I, reaches the calling subscriber. Since the winding I of the relay M is short-circuited over the contact M, the relay M is not influenced over the loop of the conductors av and be in the usual Way so that as the contact 68m is maintained open, a metering of the connection by the meter Zl is prevented. Therefore by the agreement in the settings of the switch mechanisms KW and MW when the wrong called number is sent out the metering of such connections is prevented.

What is claimed is:

1. In a telephone system, two exchanges, means for completing a local connection between two subscribers lines in one of said exchanges, a source of potential in the other of said exchanges, and means including but one two-conductor inter-exchange trunk line for connecting said source to said local connection to supply transmission current to both of said subscriberslines.

2. In a telephone system, two exchanges, a trunk line connecting said exchanges, subscribers lines terminating at one of said exchanges, a switch in said one exchange having access to said subscribers lines, and means in the other of said exchanges responsive to a calling condition on one of said subscribers lines for controlling said switch over said trunk line to connect with said one subscribers line.

3. In a telephone system, two exchanges, a trunk line connecting said exchanges, subscribers lines terminating at one of said exchanges, a switch in said one exchange having access to said subscribers lines, and means in the other of said exchanges responsive to the initiation of a call by one of said subscribers lines for transmitting impulses over said trunk line to said one exchange to operate said switch to search for said one subscribers line.

4. In a telephone system, two exchanges, a trunk line connecting said exchanges, a discriminating device at one of said exchanges connected to saidtrunk line, subscribers lines terminating at the other exchange, means for marking any one of said subscribers lines, means in said other exchange operatedto connect saidtrunk line successively with said subscribers lines, said device responsive to the connection of,

the trunk line with the marked subscribers line to halt the operation of said last means.

5. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, two switches in the sub-exchange, means in the main exchange controlled by the initiation of a call from a subscribers station in the sub-exchange for operating one of said switches over said trunk line to seize the calling line, means in the main exchange operated over the trunk line by the calling subscriber for desig over the trunk line to the sub-exchange, a receiving circuit in the sub-exchange responsive to said impulses and operating one of said switches to connect with the calling line, means in the main exchange operated over the trunk line by the calling subscriber for designating the wanted line, means in the sub-exchange operated over said trunk line by said last means if the designated line is in said sub-exchange to alter said receiving circuit to control the other of said switches, and means in the main exchange for then transmitting one or more impulses over the trunk line to cause said other switch to connect with the designated line.

'7. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, means for extending a connection from a calling subscribers line in the sub-exchange over said trunk line to the main exchange, said connection containing a certain resistance,

means in the main exchange operated over said changes, a calling subscribers line and a called subscribers line terminating at the sub-exchange, switching apparatus at the sub-exchange operated to connect both of said subscribers lines to said trunk line, two sources of potential at the main exchange, means for connecting one of said sources to said trunk line to supply control current thereover to the calling station, means for connecting the other of said sources to said trunk line to supply signalling current thereover to the called station, means responsive to the increase in said control current when the called station is bridged across the trunk line upon the subscriber thereat answering the call for interrupting said signalling current, and means responsive to an interruption of said control current by an operation at the calling station during the signalling of the called station for releasing the connection.

9. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, two switches in the sub-exchange,

means in the main exchange controlled by the initiation of a call from a subscribers station in the sub-exchange for transmitting one or more impulses over the trunk line to the sub-exchange, a receiving circuit in the sub-exchange responsive to said impulses and operating one of said switches to connect with the calling line, means in the main exchange operated over the trunk line by the calling subscriber for designating the wanted line, a relay in the sub-exchange, means controlled by said last means to operate said relay if the designated line is in the sub-exchange, said relay thereupon altering said receiving circuit to control the other of said switches, means in the main exchange for then transmitting over the trunk line one or more impulses to cause said other switch to connect with the wanted line, means for signalling the called subscriber over the wanted line, and means controlled by said relay for interrupting said signalling responsive to the answering of the called subscriber.

10. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, means in the main exchange for at times determining the routing of calls from calling subscribers stations in the sub-exchange and for at other times controlling switching equipment in the sub-exchange to extend calls to called subscribers stations in said sub-exchange, said means including a step-by-step switch, a circuit for operating said switch in accordance with impulses received over said trunk line from a calling station in the sub-exchange to determine the routing of the call therefrom, another circuit for operating said switch to transmit impulses over said trunk line to control the switching equipment in said sub-exchange to extend a call to a desired one of the stations therein, and means controlled in accordance with the position of said step-by-step switch for rendering but one of said circuits effective.

11. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, means in the main exchange for at times determining the routing of calls from calling subscribers stations in the sub-exchange and for at other times controlling switching equipment in the sub-exchange to extend calls to called subscribers stations in said sub-exchange, said means including a step-by-step switch, a circuit 'for operating said switch in accordance with impulses received over said trunk line from a calling station in the sub-exchange to determine the routing of the call therefrom, another circuit for operating said switch to transmit impulses over said trunk line to control the switching equipment in said sub-exchange to extend a call to a desired one of the stations therein, means controlled over one wiper of said switch at times rendering said first circuit effective, and means controlled over a different wiper of said switch at times rendering said other circuit effective.

12. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, subscribers lines terminating at the sub-exchange, means for transmitting impulses from a calling one of said subscribers lines over said trunk line to designate the routing of the call from said calling line, a step-by-step switch in the main exchange, a first circuit for at times operating said switch in dependence upon the impulses received over said trunk line to determine the routing of said call, a second circuit for at times operating said switch to transmit impulses over said trunk to control switching equipment in the sub-exchange to extend the call to one of the subscribers lines in the same subexchange, and means controlled in accordance with the position of said step-by-step switch for determining which of said circuits shall be effective.

13. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, a plurality of subscribers lines terminating in the sub-exchange, a plurality of devices in the main exchange respectively corresponding to said subscribers lines, means for operating said devices, means in the main exchange controlled by the initiation of a call by one of said subscribers lines for connecting the corresponding device for operation by said means, means in the main exchange operated over the trunk line by the calling subscriber for designating the wanted line, and means operated whenever the designated line is the same as the calling line for preventing the operation of the device connected.

14. In a telephone system, a main exchange, a sub-exchange, a trunk line connecting said exchanges, a plurality of subscribers lines terminating in the sub-exchange, a plurality of devices in the main exchange respectively corresponding to said lines, a switch in the sub-exchange and a corresponding switch in the main exchange, means responsive to the initiation of a call by any of said subscribers lines for transmitting impulses over the trunk line to operate said first switch to seize the calling line, said means also effective to operate said last switch to characterize the calling line, another switch in the main exchange operated over the trunk line by the calling subscriber to characterize the wanted line, means normally effective to subsequently operate the device corresponding to the calling line, and means for rendering said last means ineffective if both of the switches in said main exchange characterize the same line.

EUGEN JAUCH. 

